Holddown clamp



Aug. 5, 1958 L. F. BLATT ET AL HOLDDOWN CLAMP Filed Nov. 25, 1957 2 Sheets-Sheet 1 INVENTORS (EMA/0 F. 5447-7- BY dos-5PM M m ATraAM E/ Aug. 5, 1958 L. F.:BLATT ET AL HOLDDOWN CLAMP 2 Sheets-Sheet 2 Filed Nov. 25, 1957 INVENTORS 454440 F. 5441-7- BY Jase-7 M M. JET? United States Patent 2,845,847 HOLDDOWN CLAMP Leland F. Blatt, Grosse Pointe Woods, and Joseph M. Jatcko, Detroit, Mich.

Application November 25, 1957, Serial No. 698,573

9 Claims. (Cl. 90-59) This invention relates to holddown clamps and more particularly to a power operated holddown clamp.

It is the object of the present invention to provide a novel clamp construction which is operated by a suitable hydraulic or pneumatic motor and which is positive acting for the securing of a workpiece or other object upon or against a retaining surface.

It is a further object herein to provide a novel holddown clamp construction incorporating one or more cantilever type holddown arms pivotally mounted upon a base together with a power operated reciprocal crosshead engageable with said holddown arms for moving the same into Work retaining position.

' These and other objects will be seen from the following specification and claims in conjunction with the appended drawings in which:

Fig. l is an elevational section of the present holddown clamp in operative position.

Fig. 2 is a section taken on line 2--2 of Fig. 1.

' Fig. 3 is a section taken on line 3--3 of Fig. 1.

' Fig. 4 is a section taken on line 4-4 of Fig. 1.

Fig. 5 is a fragmentary section taken on line 55 of Fig. 1.

Fig. 6 is a side elevational view on a reduced scale of the clamp shown in Fig. 1 with associated power operable means.

Fig. 7 is a fragmentary rear elevational view of the rear cantilever of Fig. 1 in inoperative position but with its slot at a different inclination.

Referring to the drawing, the present holddown clamp consists of the horizontal base 11 in the form of a substantially square and flat block adapted for mounting upon a suitable supporting surface. At one end and centrally thereof there is provided the upright support 12, which is rectangular in cross section, and at its lower end is immovably secured to base 11 as by the welds 13.

At the upper interior side of upright 12 there is provided the transverse slot 14 which receives the reduced end 15 to the elongated horizontal support 16, also rectangular in cross section, and which is secured to upright 12 by the screw 17 threaded within the threaded bore 18.

An upright elongated body 19 is also mounted upon base 11, having a flat undersurface 20 engaging said base, and having an upright end wall engaging support 12 and secured thereto by the screws 21 threaded. within the threaded bores 22 of body 19.

Upright 12, body 19, and top support 16 are all of the same width and form a unit which is completed by the upright motor securing plate 26 at the opposite end of members 19 and 16.

The base portion 20 of body19 terminates in the up wardly inclined surface 23 Whose reduced horizontal end 24 projects within the transverse slot 25 formed across the inner face of plate 26 and is secured thereto by the screw 27 which projects within threaded bore 28 of body 19.

Likewise the free end of top support 16 is nested Within a second transverse slot 29 formed across the inner surface of plate 26 and is secured thereto by the screw 30 which snugly projects into the threaded bore 31. Accordingly, the members 11, 12, 16, 19 and 26 provide on as sembly a structural unit.

In view of the rectangular cross sectional shape of members 16 and 19 and their spacing, there is provided between said members the elongated guide slot 33 of rectangular cross section for slidably receiving the operating block or cross head 36, which is also of square or rectangular cross section and is adapted for reciprocal power operated longitudinal movements with respect to and between members 16 and 19.

The slot 33 also loosely receives the reciprocal rod 34 whose reduced end projects within the bore 35 within block 36 and is secured thereto by transverse pin 37. The opposite end of rod 34 loosely projects through a corresponding aperture 32 formed in motor mounting plate 26 and is connected to the reciprocal piston 69 as shown in Fig. 6.

As shown in Figs. 1 and 4 transverse stud shaft 38 projects through block 36 and upon the ends of said shaft upon the exterior of said block are provided the operating sleeves 39 pressed on or otherwise secured upon said shaft ends. Each of the sleeves 39 is adapted for sliding and operative movement within the elongated slots 40 formed within the respective cantilevers 41.

In the preferred embodiment said cantilevers are pivotally mounted upon portions of the transverse shaft 43 which extends through the bore 44 of body 19. Shaft 43 is in the nature of a stud having an enlarged head 45 which cooperatively engages wall 53 and is retained in position with respect to a second wall 53 by means of the washer 61 and suitable fastener 62 shown in Figs. 2

. and 3.

The cantilevers 41 are arranged upon opposite sides of body 19 in sliding engagement therewith and portions dinal axis of clamp arms 46 so that upon longitudinal movement of block 36, the sleeves 39 will operatively cam against internal surface portions of said cantilevers which define the slots 40 thus causing rotary movements of the clamp arms 46 about their pivot 43.

Referring to Figs. 1 and 2 there is adjustably provisioned upon the outer end portions of arms 46 the holddown adaptor assembly which consists of the top plate 47 having undercut slots 48 which receive end portions of the upright clamp arms 46. The adaptor also includes the holddown plate 49 which is knotched to receive portions of arms 46 and is secured to plate 47 by the screws 51.

A portion of holddown plate 49 as at 50 snugly projects between the arms 46 and has threaded bores to cooperatively receive screws 51.

The holddown adaptor 4749 has an undersurface of the proper shape to correspond to the top surface of the work W positioned upon the table T. In the present embodiment the lower end face of the adaptor includes the upwardly inclined surface 52 to cooperatively and retainingly engage the work W. Said adaptor is longitudinally adjustable on arms 46.

The holddown clamp mechanism is further completed by a pair of upright elongated side plates 53 whose horizontal undersurfaces 54 bear upon base 11. Said side plates extend upwardly and forwardly to the top of support 16 in parallel spaced relation to the outer side walls of upright 12, support 16 and body 19.

Transverse fasteners 55 extend through plates 53, the

interposed spacers 56 and are threaded into body 19. Additional opposed fasteners 57 extend transversely through lower portions ofplates 53 through interposed spacers 58 and likewise threadedly engage lower portions of body 19. i

As shown in Fig. 1, bottom horizontal portions 54 of side plates 53 terminate in the/upwardly inclined edges 59. These edges at their upper ends terminate in the upright end walls 59 which are snugly projected within the upright spaced slots 60 formed in the inner face of plate 26.

The side plates 53 cooperatively and retainingly engage the outer side walls of the cantilevers 41 which terminate in the holddown arms 46 and thus serve as retaining guides for reciprocal movements thereofand in cooperation with spacers 56 and 58 on opposite sides of members 12 and 19.

There is shown in Fig. 6, aside elevational view of the holddown clamp corresponding to the clamp of Fig. 1, but on a reduced scale. motor 63 is arranged axially beyond the end-of plate 26 and includes the cylinder head 64 which is suitably secured to plate 26 by fasteners extending through the openings 66 in end plate 26, Figs. 2 and 3, and which threadedly engage said cylinder head.

The cylinder head engages plate 26 along the line 66 of Fig. 6 to complete the power operated clamp assembly. Inlet 65 on cylinder head 64 provides means of delivering pressure fluid to one end of cylinder 63 for effecting movement to the right of piston 69. Cylinder head 67 closes the other end of cylinder 63 and includes the intake fitting 68 whereby pressure fluid i. e either liquid. or compressed air may be directed to the right end of said cylinder for effecting a power operated movement to the left of piston 69 to the position shown in Fig. 6, and which corresponds to the horizontal locking position of clamp arms 46, as in Fig. 1.

Piston 69 terminates in the collar 70 which snugly receives the end of rod 34 which is secured therein by the transverse pin 71. The collar 70 towards the end of its movement to the left movably projects within the apertured body 72 within the cylinder head 64 which provides an air cushion for limiting movement of piston 69 in one direction. In operation and with the piston 69 withdrawn to the right end of cylinder 63, the holddown arms will assume the dotted line position 46' shown in Fig. 6.

At this point, and through the operation of rod 34, the block 36 will have been withdrawn within slot 33 to or towards the right end thereof.

In view of the specific relationship between the sleeves 39, carried by block 36 with respect to the relatively inclined arm operating slots 40, it is apparent that horizontal withdrawing movement of the block 36 and the sleeves 39 will earn against portions of the cantilevers 41 which define the slots 40 causing arms 46 to pivot around their support 43 to the dotted line position shown in Fig. 6.

Also in view of the inclination between the axis of slot 40 to the longitudinal axis of the holddown arms 46 whenever the sleeves 39 have reached their outermost position as shown in Fig. 1, the holddown arms 46 are effectively clamped and-retained in the position shown. Any upward thrust against the holddown arms 46 is positively resisted because of the relative positioning of the parts. Said thrust is directed upwardly through the sleeves 39, and block 36 to the undersurface of support 16. It will be noted that any upward thrust upon the arms 46 is in effect relative to the pivotal mounting of said arms.

Accordingly said arms 46 may not be lifted until the collars 39 have been sufiiciently withdrawn with respect to the arm slots 40 that their radius of pivotal movement with respect to the mounting 43 is in substantial registry with the longitudinal axisof rod 34.

Referring to Fig 1,-ch'anging the angle of slot 40 in cantilever 41 changes the mechanical advantage of the The hydraulic or pneumatic camming action of sleeves 39 relative to said slots. For illustration, as shown in Fig. 1, the vertical rise of sleeve 39 is indicated by the letter a and the horizontal movement corresponding thereto is indicated by the letter b.

Assuming the b distance is 1 inch and the a distance is & inch, the mechanical advantage equals the tangent of the angle of b/ a which equals 1/% which equals approximately 6.4. If the distance a is 35 inch, then the mechanical advantage is approximately 10.

The above description has assumed that the angles of the slots 40 of the two cantilevers to the horizontal were equal and that cantilevers 41 and their arms 46 move in unison. It is contemplate as a part of the present invention that the respective slots 40 may be at an angle to each other to thereby achieve difierential movements between the two cantilevers.

In that case, the adaptor plate 47 and block 49 would be removed from arms 46. Such a different angle of the slot is shown fragmentarily in Fig. 7. This is a rear elevational view of the second cantilever identified as 46a, in its inoperative position. Comparing this view with Fig. 6, it is seen that the slot 40' in cantilever 46a is at an angle to slot 40 of cantilever 41.

However, both cantilevers are operated simultaneously by the respective projecting ends of pin or stud 38which carry suitable slide members 39 and 39 movably and slidably positioned within the respective slots 40 and 40'.

Because of the difierence of inclination between said slots, the two cantilever arms 46 and 46a will move at difierent speeds and throughout ditferent arcs with the one longitudinal movement ofv piston 46, thus providing differential movement.

Sleeves 39 are shown in Figs. 1 and 4 providing'a substantial rolling action within said slots. In Fig. 7, a slight variation is shown in that instead of sleeve 39 there is employed within slot 40' on pin 38, the square block 39' whose opposite sides slidably engage the walls defining slot 40.

Likewise, the opposed angularly related sides engage corresponding square walls at the ends ofslot 40'. The provision of the square blocks 39 provides for an increased locking friction relative to said cantilevers when in operative position.

Having described our invention, reference should now be had to the following claims.

We claim:

1. In a work securing clamp, a housing having an elongated slot therein and a transverse apertured mounting plate at one end thereof, a longitudinally reciprocal rod slidably extending through said plate and into said slot, a'piston in said slot secured to said red, a cantilever pivotally mounted on said housing at a point displaced from the longitudinal axis of said rod, an angular work engaging arm at one end of said cantilever, said cantilever having an elongated slot therein extending at an acute angle to the longitudinal axis of said arm, a pin projecting laterally from said piston with its end 'operatively positioned within said slot, and a motor secured to said mounting plate and including a reciprocal means axially joined to said rod, longitudinal movement of said pin being adapted to cam said cantilever and arm from inoperative to work securing position.

2. In the work securing clamp of claim 1, said pin being adapted to ride from one end of said slot to the other, independent return movement of said arm being resisted by transverse forces on said pin acting through said piston at an angle substantially transverse of the axis of said housing slot.

3. In a work securing clamp, a housing having. an elongated slot therein and a transverse apertured mounting plate at one end thereof, a longitudinally reciprocal rod slidably extending through said plate and into said slot, a piston in said slot secured to said rod, a pair of spaced cantilevers pivotally mounted upon and against opposite sides of Said housing at a point displaced from the longitudinal axis of said rod, parallel spaced work engaging arms extending angularly to the one ends of said cantilevers, said cantilevers having parallel elongated slots therein extending at an acute angle to the longitudinal axis of said rod, a pin projecting laterally from opposite sides of said piston with its ends operatively positioned within said slots, and a motor secured to said mounting plate and including a reciprocal means axially joined to said rod, longitudinal movement of said pin being adapted to cam said cantilevers and arms from inoperative to work securing position.

4. In a work securing clamp, a housing having an elongated slot therein open on its opposite sides and a transverse apertured motor mounting plate at one end thereof, a longitudinally reciprocal rod slidably extending through said plate and into said slot, a piston in said slot secured to said rod, a pair of fiat upright spaced cantilevers pivotally mounted upon and against opposite sides of said housing at a point displaced from the longitudinal axis of said rod, parallel spaced work engaging arms extending angularly to the one ends of said cantilevers, said cantilevers having parallel elongated slots therein extending at an acute angle to the longitudinal axes of said arms, a pin projecting laterally from opposite sides of said piston with its ends operatively positioned within said slots, 2. motor secured to said mounting plate and including a reciprocal means axially joined to said rod, longitudinal movement of said pin being adapted to cam said cantilevers and arms from inoperative to work securing position, and a pair of upright cantilever guide retainer plates spaced from and mounted upon opposite sides of said housing, with the one ends of said plates secured to said motor mounting plate and intermediate portions of said plates secured to said housing defining elongated guide slots for the pivotal movements of said cantilevers.

5. In the work securing clamp of claim 1, a work engaging adaptor block adjustably interposed between end portions of said arms and supportably engaging said arms, a securing plate interposed between said arms, arranged above and supportably engaging said arms, and means securing said plate to said adaptor block, whereby said block is adapted to transmit clamping pressure at right angles to the axes of said arms.

6. In the clamp of claim 3, the slots in said cantilevers being arranged at different angles for producing differential movements between said arms on a single power operated movement of said piston.

7. In the clamp of claim 4, the slots in said cantilevers being arranged at different angles for producing differential movements between said arms on a single power operated movement of said piston.

8. In the clamp of claim 1, a sleeve on the end of said pin movably positioned within said slot, the ends of said slot being semi-circular to cooperatively receive said sleeve.

9. In the clamp of claim 1, the ends of said slot being square, and a square-shaped block secured upon the end of said pin and slidably nested within said slot.

No references cited. 

